The present invention relates to smoking articles such as cigarettes, and in particular to those smoking articles having a short fuel element and a physically separate aerosol generating means. Smoking articles of this type, and methods and apparatus for preparing them are described in the following U.S. Pat. Nos. 4,708,151 to Shelar; 4,714,082 to Banerjee et al.; 4,732,168 to Resce; 4,756,318 to Clearman et al.; 4,782,644 to, Haaler et al.; 4,793,365 to Sensabaugh et al.; 4,802,568 to Haarer et al.; 4,827,950 to Banerjee et al.; 4,870,748 to Hensgen et al.; 4,881,556 to Clearman et al.; 4,893,637 to Hancock et al.; 4,893,639 to White; 4,903,714 to Barnes et al.; 4,917128 to Clearman et al.; 4,928,714 to Shannon; 4,938,238 to Barnes et al., and 4,989,619 to Clearman et al., as well as in the monograph entitled Chemical and Biological Studies of New Cigarette Prototypes That Heat Instead of Burn Tobacco, R. J. Reynolds Tobacco Company, 1988 (RJR Monograph). These smoking articles are capable of providing the smoker with the pleasures of smoking (e.g., smoking taste, feel, satisfaction, and the like).
Cigarettes, cigars and pipes are popular smoking articles which use tobacco in various forms. As discussed in the background sections of the aforementioned patents, many smoking articles have been proposed as improvements upon, or alternatives to, the various popular smoking articles.
The smoking articles described in the aforesaid patents and/or publications employ a combustible carbonaceous fuel element for heat generation and aerosol forming substances positioned physically separate from, and in a heat exchange relationship with the fuel element.
Carbonaceous fuel elements for such smoking articles typically comprise a mixture of carbon and a binder. Optional additives such as flame retardants, burn modifiers, carbon monoxide catalysts, and the like have also been employed in such fuel element compositions. Energy levels of such fuel elements, i.e., smolder heat and draw (or puffing) heat have often been difficult to control, and has largely been manipulated by modification of the fuel element design, e.g., the number of and placement of passageways through the fuel element and/or on the periphery thereof.
It would be advantageous to have an easier method of manipulating the energy levels of such carbonaceous fuel elements so that the design parameters of smoking articles employing such fuel elements can be varied based on a controlled amount of energy generated by the fuel elements.
Surprisingly, it has been discovered that the sodium content of carbonaceous fuel elements of the type described above is one factor controlling the energy levels of the fuel elements during puffing and smolder. It has also been discovered that the sodium content of these fuel elements has an effect on the lightability of such fuel elements.
The amount of sodium contained in the fuel elements, and the form in which the sodium is included in the manufacturing of the fuel element, have very substantial effects on the fuel element combustion characteristics. Thus, the amount of sodium added during the manufacture of the fuel elements, and the form in which it is added, can be varied to improve performance of the smoking articles and increase control over the burning characteristics of the fuel elements.